[llvm] Avoid a race condition in opt-viewer/optrecord (PR #131214)

[via llvm-commits]

================
@@ -64,17 +64,19 @@ class Remark(yaml.YAMLObject):
 
     default_demangler = "c++filt -n"
     demangler_proc = None
+    demangler_lock = Lock()
----------------
serge-sans-paille wrote:

I 100% agree with that.

https://github.com/llvm/llvm-project/pull/131214